Using ultrasound transmission velocity to analyse the mechanical properties of teeth after in vitro, in situ, and in vivo irradiation

Abstract

Ultrasound transmission velocity (UTV) in isotropic material as a measure for the modulus of elasticity was correlated to mechanical properties. Changes in micromechanical properties of radiated teeth and influence of the oral cavity were to be evaluated nondestructively. UTV was measured in extracted teeth after 36 Gy and 62 Gy of in situ (enorally, with no contact to the oral cavity) and in vitro irradiation. Relative to controls, teeth subjected to 62 Gy in vivo showed higher UTV values for dentine and enamel. Sound teeth irradiated with 60 Gy in situ also showed higher UTV values for enamel, whereas dentine values were not significantly different from those of control. The mechanical properties of teeth irradiated in vitro were affected only after high experimental doses of up to 500 Gy. The difference between in vivo and in vitro mechanical properties may be due to radioxerostomia-induced damages as well as the status of dentine vitality. This supports the concept of direct radiation-induced damage in synergy with radioxerostomia-induced caries.

Bond strengths of two conventional glass-ionomer cements to irradiated and non-irradiated dentin

“…Although irradiated dentin is a clinically relevant bonding substrate, little is known about the direct effects of ionizing radiation on dentin 1,11) . Grotz et al 30) reported that the mechanical properties of dentin seemed to be less affected by irradiation than enamel. It should be mentioned that direct radiogenic effects may affect the mechanical stiffness of dentin 8,9) .…”

“…It should be mentioned that direct radiogenic effects may affect the mechanical stiffness of dentin 8,9) . However, under radiotherapy conditions, irradiation obviously has only a minor effect on the mechanical properties of dentin 30) . Zach 31) reported that irradiated teeth showed no alterations in crystallinity or calcium-phosphorus ratio.…”

Effect of Gamma Radiation on Mechanical Properties of Tooth Structure

“…Additionally, in the current study, the samples were placed in artificial saliva during irradiation to simulate, as precisely as possible, the conditions that are found in the oral cavity [16] . However, other media, including 0.9% saline solution [6,13] , distilled water [11,15] , or buffered phosphate solution [11] , have been used to store teeth in similar studies. Although artificial saliva does not exactly mimic the characteristics of natural saliva, especially in the case of patients undergoing head and neck radiation therapy, who present changes in the flow, secretion, and composition of natural saliva [22] , artificial saliva is still considered the most suitable storage medium [16,23] .Studies of the structural changes in enamel and dentin following irradiation are controversial [6,[11][12][13]15,16] .…”

“…Radiation-related caries or "radiation caries" is one of the highest indirect and late effects of radiation in the head and neck region [6] . This complication is a complex and destructive disease that causes severe destruction of the tooth enamel and dentin in head and neck-irradiated patients [5,7,8] and has negative effects on their quality of life [8] .…”

“…Scientific evidence indicates that patients incur a lifelong risk of developing radiation caries following radiation therapy [7] .The effects of radiation therapy on the onset and progression of a caries lesion might be direct or indirect [8] .The indirect effects of irradiation include changes in the quality and quantity of saliva, difficulty in performing proper oral hygiene, increased intake of cariogenic foods,and changes in the oral microbiota [5,7,9] . Radiation therapy may also exert direct effects on the dental structure,including changes in the crystalline structure, enamel and dentin microhardness, dentinoenamel junction, and acid solubility of the enamel; these effects might be involved in the pathogenesis of the disease [6,[10][11][12][13][14][15][16] . The direct effects of radiation on the deciduous dentitionare still unknown because studies addressing this issue have only been conducted in bovine teeth and in human permanent teeth.…”